Can Vitamin D Help Against COVID-19?

Author: Ivana Mišová, PhD.

Published at: 10/15/2020

Respiratory illnesses are often limited during warm, sunny weather, and it seems that a cold environment could be an additional risk factor for SARS-CoV-2 infection as well1. However, this relationship is still not fully understood. The key factor influencing our susceptibility to these diseases could be the level of vitamin D, an important hormone regulating multiple processes in the cell, which is produced in the skin following sunlight exposure.

The human form of vitamin D is D3, also called cholecalciferol. It is later metabolized in the liver to produce 25-hydroxyvitamin D3 (calcifediol) and again in the kidney to produce 1,25-dihydroxyvitamin D3 (calcitriol). Vitamin D is also found in oily fish and eggs. It is important to maintain your vitamin D level, as its deficiency is associated with fractures and bone diseases, as well as several types of cancer2.

Why do we think it could help against SARS-CoV-2? Vitamin D shows immunomodulatory activity in response to the invasion of bacterial and viral pathogens3. It also downregulates ACE-24, which is key in SARS-CoV-2 entry into the host cells5. Both metabolites of vitamin D3 demonstrated antiviral properties in SARS-CoV-2-infected cells6,7. Moreover, there is a striking overlap between risk factors for severe COVID-19 and vitamin D deficiency, such as obesity, older age, and Black or Asian ethnic origin8.

Is there any clinical data on vitamin D level and COVID-19? A retrospective study found that people with likely deficient vitamin D status had the relative risk of testing positive for COVID-19 1.77 times greater than patients with likely sufficient vitamin D status9. Another study on 235 hospitalized patients diagnosed with COVID-19 showed a strong association between vitamin D sufficiency and reduced risk for adverse clinical outcomes, including mortality10. Negative correlations between mean levels of vitamin D and the number of COVID-19 cases and deaths were observed in multiple European countries11,12. Hence, this data suggests that having enough vitamin D not only lowers your chance of catching COVID-19 but if you do get sick, it can also reduce the adverse outcomes of the disease.

However, what if you already have COVID-19 – could vitamin D supplementation still help you? Research data suggests that yes – administration of a high dose of vitamin D metabolite (calcifediol) significantly reduced the need for ICU treatment of patients hospitalized with COVID-1913.

So, what is the verdict – is vitamin D effective in the prevention and treatment of COVID-19? As usual, to answer this, further research is needed. However, vitamin D deficiency puts you at risk of much more than just COVID-19, so consulting your doctor about your vitamin D levels is nevertheless a good idea!



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